Conventional seat belt systems for vehicle seats include two components, the buckle assembly and the tongue assembly. If an occupant is not present in the vehicle seat, the buckle and the tongue are not physically attached. After an occupant enters the vehicle seat, the occupant inserts the tongue into the buckle, where a mechanical actuator in the buckle locks the tongue rigidly in an attached state, thereby restraining the occupant in the vehicle seat. To break the mechanical attachment and return to the unattached state, the occupant presses a button on the buckle, which disables the attached state. Often the tongue and mechanical actuator are formed of metal. In addition, a switch is generally included within the buckle to detect when the buckle assembly is properly buckled.
Electromechanical devices and sensors also may be integrated into the seat belt in order to support additional safety functions. Currently, belt-integrated sensors and actuators require wiring through the entire belt assembly from the retractor or the belt base in order to receive power from a power supply or receive and transmit data from a control unit. Such wiring, however, adds additional cost and complexity to the system.